Stent

ABSTRACT

A stent ( 10 ) for transluminal implantation comprises a first, second and third stent section ( 11, 12, 13 ) for splinting and/or keeping open a hollow organ which are connected to each other via elastic tubular sections ( 14, 15 ). The stent ( 10 ) combines at least three different stent designs in one stent and can therefore be adjusted to the motion behavior of a hollow organ in an improved fashion (FIG.  1 ).

BACKGROUND OF THE INVENTION

The invention concerns a stent for splinting and/or keeping open ahollow organ, consisting of a tubular body having a diameter which canbe changed through axial displacement of the ends of the body relativeto each other.

A stent of this type is disclosed in EP 0 901 353 B1.

The known stent not only permits radial widening of vessel narrowingsbut also splinting or keeping open thereof. The stent is introduced intoa hollow organ in its narrowed and lengthened state and radiallyexpanded at the narrowed location of the hollow organ to ensure that thehollow organ assumes its original lumen at this location if possiblypermanently. For automatic expansion, webs are used which are processedinto stents. The webs can be lengthened against their unloaded initialstructure. If the lengthening or radial deformation is removed, theseknown stents return into their initial state through radial widening.This effect is used for widening stenoses in hollow organs to preventtheir function from being impaired, if possible.

SUMMARY OF THE INVENTION

It is the object of the invention to produce a stent with improved andpositionally stable adoption and transmission of the motions of thehollow organs.

This object is achieved in accordance with the invention by the featuresof claim 1.

The inventive stent therefore has the substantial advantage that it canhave sections in the longitudinal direction with returning forces ofdifferent strengths. Each stent section may have its own design and/ormotion behavior such that stents with reduced total pre-shortening(axial lengthening of the free stent ends with radial compression of astent) and special migration-suppressing properties can be produced. Dueto the fact that the stent sections are connected to each other viaelastic tubular sections, the individual stent sections remain highlyelastic and can be adjusted to the hollow organ shapes in an improvedfashion. The elastic tubular sections (thin highly flexible andtear-proof plastic sheets) permit relative motion of the individualstent sections (invagination of a higher or lesser degree which dependson the selected wall thickness and the selected material for the elastictubular sections). The inventive stent adjusts itself, if necessary, tothe peristaltic of hollow organs without migrating. Particular new stentproperties can be derived from the distance, separation of theindividual stent sections from each other in connection with the elastictubular sections which interconnect the individual stent sections.

The inventive stent can be expanded by auxiliary means or can bedesigned as automatically expanding stent.

The inventive stent sections have a woven, braided tubular mesh and/orone or more phase-shifted helices in one or more planes.

This is advantageous in that different support constructions can be usedin the individual stent sections in the same stent. The differentsupport constructions or support constructions of different distinctioncontrol the motion and deformation behavior of the inventive stent in adefined fashion.

In a further preferred embodiment of the invention, the body is formedin the unloaded expanded state from a first stent section comprising afirst diameter, a second and third stent section comprising a second andthird diameter and from two elastic tubular sections which connect thefirst, second and third stent sections.

This is advantageous in that a three-part stent may provided innerlining of a hollow organ which permits e.g. a bordering tumor toprotrude elastic tubular sections of an inventive stent into the lumenof the stent. Support and fixing of a stent in the stenosis is furtherimproved thereby (protection from migration).

In a further embodiment of the invention, the diameters of the stentsections vary. This is advantageous in that returning forces ofdifferent strengths may form for different locations. The elastictubular sections easily adjust to cross-sectional changes specificallyalong a stent and in the unloaded state, a transition from a smallerstent section to a larger stent section and vice versa withoutprojection or creases is possible.

In a further embodiment of the inventive stent, when several helices areprovided in several planes, at least one helix has an opposite windingdirection. This is advantageous in that the inventive stent obtainsreversible torquing (torque) such that during expansion, thepre-torquing is returned and the inventive stent abuts the inner surfaceof a hollow organ like a screw. This so-called “torquing effect” can berealized in each of the individual stent sections as required.

It is also preferred that the elastic tubular sections are produced froma tissue-compatible plastic material and/or the elastic tubular sectionshave different diameters in the unloaded state.

This is advantageous in that the inventive stent largely prevents orreduces tissue irritations in the region of its two ends, when placed atits location, and it is possible to coat also the support constructions(webs, helices) with a layer or layers which form elastically tubularsections. Different diameters of the stent sections in the longitudinaldirection of a stent are thereby no problem.

In a particularly preferred embodiment of the inventive stent, the bodyhas, viewed in cross-section, a web in the first, second and third stentsection and/or one or more helices which are surrounded by one or moreelastic plastic layers which merge into the elastic tubular sections ina material-bonding fashion without webs and helices.

This is advantageous in that the inner surface of an inventive stent mayhave a particularly smooth and/or e.g. hydrophilic layer depending onthe requirements and the jacket with plastic layer formed in the outerperiphery of the stent fixes the web or helices and the outer and innerplastic coating can merge into the elastic tubular sections along theinventive stent in a material-bonding fashion. This embodiment producesparticularly robust stents.

The body of an inventive stent may have a filament in an axial directionin the wall which may serve as a securing thread which ensures that thedifferent stent sections are held together also under increased load andon the other hand this thread may provide X-ray shadow. This isadvantageous in that also after a longer prevailing time, the positionof the stent in the hollow organ can be examined, determined and provenin an exact fashion. It is clear that also several filaments, e.g. ontwo opposite sides or in all four cross-sectional quadrants can beworked into the wall of a stent.

The filament worked into the stent in a longitudinal direction mayproject over the stent as securing thread and serves as pulling threador for mounting the inventive stent. Several filaments can be workedinto the wall of the stent viewed across the periphery of the stent.

In a further embodiment of the invention, the proximal end region of thebody of the inventive stent, viewed across the periphery of the body,comprises a worked-in thread whose length projects past the stent. Thisis advantageous in that such a thread can produce a thread ring similarto a tobacco bag seam which facilitates removal of a placed stent.Pulling together of the proximal stent end like a tobacco bag permitsremoval of the inventive stent from the bordering hollow organ tissueand pulling out of the hollow organ by the thread.

In a further embodiment, the distal end of the body has a return valve,in particular a foil valve, which is advantageous in that when theinventive stent is placed in the oesophagus, liquid or other nutrientscan flow only in one direction. The foil valve formed as reflux valveconsists of two thin foil sheets which are welded together e.g. at theedges.

Web-free means at the same time no meshes or helices.

Further advantages, of the invention can be extracted from thedescription of the drawing. The features mentioned above and below canbe used in accordance with the invention either individually or inarbitrary combination. The embodiments mentioned are not to beunderstood as exhaustive enumeration but rather have exemplarycharacter.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a side view of a first embodiment of an inventive stent;

FIG. 2 shows a side view of a second embodiment of an inventive stent;

FIG. 3 shows a side view of a third embodiment of an inventive stent;and

FIG. 4 shows a side view of a fourth embodiment of an inventive stent.

The figures show the inventive stent in a highly schematised fashion.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a stent 10 which is formed from a first stent section 11, asecond stent section 12, a third stent section 13, a first elastictubular section 14 and a second elastic tubular section 15. The stent 10is shown in an unloaded expanded state. The support construction in thestent sections 11, 12, 13 is a web 16 which may be tubularly braided orwoven. The individual filaments of the web may be produced from metal,plastic or carbon. The first stent section 11 may be the tubular web 16itself or the web 16 is additionally surrounded by a plastic jacket. Thegaps (meshes) of the web 16 may be open or closed. The second and thirdstent section 12, 13 have a larger diameter than the first stent section11. The web 16 of the first stent section 11 was also chosen as supportconstruction in the stent sections 12, 13. The diameters of theindividual filaments of the web 16 in the stent sections 12, 13 may bedifferent from the filament diameters of the filaments used in the firststent section 11.

The stent sections 11, 12, 13 are connected to each other via a firstand second elastic tubular section 14, 15. The elastic tubular sections14, 15 are produced from a flexible thin plastic material, e.g. silicon,and permanently and securely connect the stent sections 11, 12, 13. Theelastic tubular sections 14, 15 can safely bridge diameter changesbetween the individual stent sections 11, 12, 13 and can adjust to thesurface contour in a hollow organ without forming gaps. The stent 10 canbe lengthened in the direction of arrows 17 and be shortened again afterlengthening. The present case concerns an automatically expanding stent10 which has a smaller diameter in the lengthened state than in theexpanded state shown in the figure.

FIG. 2 shows a stent 20 consisting of a first stent section 21, a secondstent section 22, a third stent section 23 and a first and secondelastic tubular sections 24, 25. The stent sections 21, 22, 23 areinseparably interconnected via the elastic tubular sections 24, 25. Thestent sections 21, 22, 23 have a helix 26 as support construction whichis embedded into a stretchable elastic plastic material. The elastictubular sections 24, 25 have no reinforcing materials such that thestent sections 21, 22, 23 are individually and mutually movable. Thestent sections 21, 22, 23 can be lengthened and shortened in thedirection of arrows 27. The elastic tubular sections 24, 25 follow themotions of the stent sections 21, 22, 23.

FIG. 3 shows a stent 30 comprising a first stent section 31, a secondstent section 32 and a third stent section 33. The stent sections 31,32, 33 are permanently connected via a first and a second elastictubular section 34, 35.

The support construction in the first stent section 31 is a first andsecond helix 36 of opposite winding directions. A helix 36 is disposedin a first plane in the first stent section 31 embedded in a plasticmaterial, and another helix 36 extends in the second plane which has anopposite winding direction. The support structure of the stent sections32, 33 is a web 38 which is connected to the first stent section 31 viathe elastic tubular sections 34, 35. The stent 30 can be lengthened andshortened in the direction of arrows 37.

FIG. 4 shows a side view of a further inventive stent 40 which iscomposed of a first stent section 41, a second stent section 42, a thirdstent section 43, a first elastic tubular section 44 and a secondelastic tubular section 45. The support structure is oppositely windinghelices 46 which extend in two different planes. The helices 46 areembedded in a plastic material which is also used for the elastictubular sections 44, 45. The elastic tubular sections 44, 45 have nohelices. The stent 40 can be lengthened in the direction of arrows 47and subsequently be expanded in a radial direction and shortened in alongitudinal direction. The plastic coating of the helices 46 isselected such that the surface contour 48 is formed on the outer surfacewhich is determined by the selected cross-sectional shape of the helices46 used. The distal end has a foil valve 50 which permits passagethrough the stent 40 only from the proximal end towards the distal end.If a fluid or solid flows through the stent 40 from the proximal end tothe distal end, the foil valve opens and the foil sheets open i.e. theyare moved away from each other. If nothing flows through the stent 40,the foil sheets abut and close the lumen, formed by the stent 40, at oneend.

In a longitudinal direction of the stent 40, a filament 51 is workedinto the wall of the stent 40 over the entire length which serves assecuring thread for the different sections of the stent 40. The filament51 may project past the stent 40 such that the stent 40 can be mountedor be pulled in the hollow organ via the filament 51. The proximal endof the stent 40 has a thread 52 as thread ring viewed over the peripheryof the stent. If the thread 52 is pulled together, the lumen of thethird stent section 43 is also highly reduced and the positioned stent40 is released from the inner surface of the hollow organ. The stent 40can be removed from a hollow organ via the thread 52.

A stent 10 for transluminal implantation comprises a first, second andthird stent section 11, 12, 13 for splinting and/or keeping open ahollow organ, which are connected to each other via elastic tubularsections 14, 15. The stent 10 combines at least three different stentdesigns in one stent 10 and can be adjusted to the motion behavior of ahollow organ in an improved fashion.

1-10. (canceled)
 11. A stent for splinting and/or keeping open a holloworgan, comprising: a tubular body comprising several stent sectionscomprising different cross-sections which can be expanded irrespectivelyof each other; and a woven, braided tubular web and/or one or morephase-shifted helices in one or more planes which are connected to eachother via at least two tubular sections, wherein the at least twotubular sections comprises a first elastic tubular section connectingthe first stent section to the second stent section and a second elastictubular section connecting the second stent section to the third stentsection.
 2. The stent of claim 1, wherein the tubular body has adiameter which can be changed through axial displacement of the ends ofthe body relative to each other.
 3. The stent of claim 1, wherein thediameters of the stent sections are different.
 4. The stent of claim 1,wherein the elastic tubular sections are produced from atissue-compatible plastic material and/or have different diameters inthe unloaded state.
 5. The stent of claim 1, wherein the body comprisesat least one filament in the wall in the axial direction.
 6. The stentof claim 1, wherein a thread is worked into the proximal end region ofthe body, viewed over the periphery of the body, whose length projectspast the stent.
 7. The stent of claim 1, wherein the distal end of thebody comprises a return valve.
 8. The stent of claim 7, wherein thereturn valve is a foil valve.
 9. The stent of claim 1, wherein thetubular sections comprise thin, highly flexible and tear-proof plasticmaterial.
 10. The stent of claim 9, wherein said tubular section is madefrom silicon.